DATE & TIME

i would lik e to know the step by step procedure on how to add a date that is entered and that needs to be displayed on another filed and (this filed needs to be saved)

secondly, i would also like to know on how to get the exact code (step by step info)

When I open a form (new page) this shoudl record the time (that is i can use the date () function)
after entering all the fields in the form and when i save it it should log that current time, and the value of time end-time start should be displayed on a field and it should be saved.

Could some one help me in the complete step by step procedure for the same.....